Process of making hard sintered metals



Jan.,14, 1936. BOECKER PROCESS OF MAKING HARD SINTERED METALS Filed Oct. 25, 1933 G- USTAV B'oECKE R,

ATTORNEY.

Inv ntor enema 1...?14, 1935 P AreNrjo rnocnss OF mam]; t SINTERED. METALS I castavnmker, namc mw 'Acidia, Thionville, France,

company of France a joint-stock Application October 2s, 19s-s, Serial No. 694,891

4 Claims.

invention relates to processes of making sintered hard metalsand consists essentiallyin novel steps connected with theprocess and in the productionof a new kind of hard metal,

As working material for high-grade cutting anddrawing tools there are used so-called hard metals which .cqnsist either of an alloy or a sintered mixture or several component metals.

In making the sintered 'metals frequently the dimcultly fusible carbides of tungsten and molybdenum are used as the carrier'of hardness and a more easilyfusible beddingor auxiliary metal careiullydried therein, while jthe whole mass, is" first sintered only until a formed piece of some is sintered into saidcarbides; 'A very good success had alsobeen obtained with a" sintering metal in which silicides of titanium or boron and titanium or a-rmixture of. both have been united by means. otcobalt in theabsence of oarbon. In this case by further addition otmagnesium,f aluminum,.vanadium or beryllium the ,hardness and above all,,the toughness of this metal may still beconsiderablyincreased.

These orasimilar sintered hardmetals \are gene erally produced first most flnely powdering the initial materials and thereupon wettingnthe same. As the completely sintered metal cannot subsequentlyibe worked and shaped,

firmness is obtained."Considering the degree of shrinkage, this iormed, piece may now be slightly worked; into "final shape ;.and. subsequently thereto .the .sintering. is completed,- A; drawback of a process of; this kind consists -.inthat.a Considerableshrinkage o f the massis to befigured with a during sintering and that, eveniit high pressures are. employed for the .;forming process} there will still be; ashrinkage amounting .to from, 20 to 25%. "Thislfact among other things,.-serves to prove that the fineegrained metals or metal compounds after being termed and pressed are still' of. relatively loose structurewith the result of diminishing the homogeneousness and therewith also the toughness of the completed material.

In order to make: a .dense and therewith tough hard, metal a process had heretofore been used which consists in 'that the previously. properly treated-and moistened mixture of metal is pressed into shape? by: spraying with the aid of compressed an. In this manner formedipieces of extraordinary density may be made, which without employingprevious sintering are of such flrmnessjthat" they may be worked into final shape. Quite irrespective of the fact that a considerably greater toughness and homogene- 5 h ousness. The sh'rinkage of the so treated mixv ture of metal of earth moisture, that is, witha. moisture content such that the mixturewill have about the consistency of ordinarydamp earth or soil, according to experience} amounts to only irom 5 to 8%, this figure permitting further conclusions to be made asregards the quality of the completed sintered alloy.

The spraying process'which has heretofore been employed for blowing the completed finely grained metal mixture which. is made up by means of a liquid paste into forms with the aid or pressure air, still involves considerable drawbacks; inspite of the progress otherwise attained by such' process. Thcompressed air which is used in connection with this process, even after most fcareful dehydratingand dryin always contains certainquantities of moisture, which; when carriedinto the iorms gives rise to the formation of pores during the sintering of the mass, therewith impairing the homogeneousness of the structureof the completed metal. A further vdrawback is found to reside inthe dimculty or; uniformly supplying the metal dust whichis moistened by the paste, that is the plastic mass, from the spraying apparatus'into the metal form. In present practice it frequent-- ly-happens; that the sticky mixture or metal is not sumciently disintegrated sothat it is sprayed into the form in droplets-or lumps of greater or smaller size. By thisthere will be produced 1mlike formed pieces, which in addition, usually also possess difierent shrinkages. t These disadvantages are completely avoided by my new process of making 'sint'ered hard metals. My new process permits producing firm and homogeneous formed or molded pieces in a most simple and reliable way, the formed pieces I after sintering representing a working material, which I is free from fissures, cracks and pores and above all, is of great toughness. This is accomplished in the first. place by spraying the finely powdered dry mixture of metal and the liquid necessary for the shaping, at high pressure through two separate spraying nozzles which are so directed against each other that the sprays of metal powder and liquid adhesive the; present process to any definite pressures, it

may be stated that in general very gOOd results are obtained by using pressures of three to five atmospheres. The exact pressure most suitable in any given instance will, of course, vary with the conditions and it is, therefore, not possible to set down any definite pressure as being best for all purposes. Owing to the fact thatboth of these media are most finely divided or atomized when passing through the spraying nozzles, the several small grains of the metal during the impact between said media will be moistened quite uniformly. Moreover, said small grains of metal no longer find time to stick to each other and are thrown at high pressure most densely and uniformly into the mold. Furthermore, ac-

cording to my invention, I make use, instead of ing it possible to produce a hard metal free from cracks, fissures and pores.

In the drawing two exemplary ways of carrying out the new process are diagrammatically illustrated in Figs. 1 and 2.

In Fig. 1, two nozzles I and! serve for feeding the dry metallic mixture and the' adhesive or adhesion promoting liquid. Through the nozzle l the liquidis fed under pressure, through the nozzle 2, likewise under pressure, is fed the finely divided metallic powder. High-pressure dry gases serveas the feeding agent for the latter. The nozzles l and 2 are so directed with respect to one another that the stream of metallic powder meets the stream of liquid on the way to the metal mold 3. Thereby both ingredients become most intimately mixed with one another and the metallic dust becomes uniformly moistened with the liquid. The metallic grains, which are discharged under high pressure, can thereby no longer form lumps or stick together, and are thrown in the most dense and uniform distribution into the mold 3.

In Fig. 2 the two nozzles l and 2 are combined into a single nozzle 4 having three bores. From the outer bores 5 and 6 of the nozzle the metallic dust is discharged under high pressure, through the central passage 1 the finely divided liquid.

The nozzle points are directed toward one an-- other insuch way that in this case the meeting of the two substances takes place closely in front of .the opening of the nozzle and then a long path to the metal mold 3 is provided wherein the uniform moistening of the metallic mixture ensues.

The formed pieces made accordingto the spraying process do not need to be previously sintered and, if it should be desired, may im- 1 Percent Titanium- 76 Silicon 14. 5 Cobalt 9. 5

2 Percent Titanium 45 Boron 40 Cobalt l5 Titanium 71 Silicon .1. 17.5 Cobalt r 11 Vanadium 0,5

' 4 Titanium 41 Silicon 13.2 Boron 32. 6 Cobalt- 12.5 Vanadium 0.3 Magnesium 0.4

. 5 Tungsten l0 Silicon 18 Titanium 10 Vanadium 0.5 Cobalt 8.5

p 6 Tungsten 81 Carbon 10 Titanium 4 Vanadium 0,3 Cobalt 4.5

I claim: a

1. Process for making sintered hard metals, in a mold, which comprises producing a spray of a dry, finely powdered mixture of difilcultly fusible metals and a more readily fusible auxiliary metal, under high pressure, producing a spray of an adhesive agent customary for binding hard metals likewise under high pressure, so directing said sprays that the spray of metallic powder and the spray of adhesive liquid will meet on their way to the mold or within the latter, whereby the mold will become filled with a compact moist mass of the metallic powder, and finally completing the hard metal article thus molded by sintering.

2. Process for making sintered hard metals, in

,a mold, which comprises producing a spray or a dry, finely powdered mixture of diflicultly fusible metals and a more readily fusible auxiliary metal, under high pressure, producing assay of an adhesive: agent customary for binding hard metals likewise under high pressure, so directing said sprays that the spray of metallic powder and the spray oradhesive liquid will meet on their way-to the mold or within the latter, whereby the mold will become filled with a compact moist mass 01' the metallic powder, working said mass into its desired ultimate shape and finally completing the hard metal article thus shaped by sintering.

proper pressure.

GUSTAV BOECKER. 

